1. Field of the Invention
The present invention generally relates to electrochemical cells and batteries and more particularly relates to electrochemical cells and batteries employing zinc electrodes, as well as silver oxide electrodes and separators.
2. Prior Art
As is well known, in zinc-silver oxide batteries the zinc electrodes tend to become passivated at low temperatures and when discharged at high current density. Zinc which is dissolved during the current discharge changes into zincate, which is in chemical equilibrium with zinc hydroxide. The latter is, in turn, in equilibrium with zinc oxide. However, at low temperatures the diffusion of the zincate is obstructed, and at high current densities more zincate is produced. Both causes, alone or together, have the effect of increasing the concentration of zincate in the area of the zinc surface of the electrode. At higher concentrations of the zincate the point of equilibrium is shifted towards zinc hydroxide and further towards zinc oxide, which then accumulates as a top layer at the surface of the electrode, and prevents further dissolution of the zinc. This behaviour is called passivation. It is highly desirable to be able to prevent or impede passivation in such cells in order to improve cell efficiency.